1. Field of the Invention
The present invention relates to a feed roller for feeding a disk, an optical disk carrying unit equipped with this feed roller, and an optical disk recording/playback device equipped with this optical disk carrying unit.
2. Description of the Prior Art
The market for optical disk recording/playback devices, especially vehicle-counted optical disk recording/playback devices, has been demanding their reduction in size and thickness, and technological development attempts are being extensively made to meet this demand. In order to reduce the size and thickness of optical disk recording/playback devices, commonly adopted means is to directly hold an optical disk between a feed roller and a disk guide and carry it instead of mounting the optical disk on a tray when inserting it into or ejecting it out of a recording/playback device (see, for instance, the Japanese Published Unexamined Patent Application No. Hei 8-138298).
FIG. 1 illustrate the configuration of a disk carrying unit for a conventional vehicle-mounted optical disk recording/playback device, FIG. 1A showing a front sectional view, FIG. 1B showing a plan and FIG. 1C showing a side sectional view. Referring to FIG. 1, a disk carrying unit 11 is arranged in the front part of a lower chassis 10, which is the main chassis of the device. The disk carrying unit 11 is provided with a sheet metal-made feed plate 12 extending in the widthwise direction of the lower chassis 10, and rotational spindles 13 protruding from the centers of both sides of the feed plate 12 rotatably pivot on the lower chassis 10. At the rear ends of both sides of the feed plate 12, a rubber-made feed roller 14 gradually expanded in diameter from the center towards both ends is rotatably disposed. The feed roller 14 is movably fitted to a roller shaft 16, and slips relative to the roller shaft 16. Incidentally, as the roller shaft 16 is thin and long, a sleeve is press-fitted into its central part as reinforcement, and this sleeve is supported by the feed plate 12 (see FIG. 2). The feed plate 12 is rotationally forced in the clockwise direction in FIG. 1C by torsional coil springs 15 disposed around the rotational spindles 13. In its normal state, the feed plate 12 approaches a disk guide 31 formed integrally with the upper chassis 30, and a disk D inserted through a disk inlet 10a is held between the feed roller 14 and the disk guide 31. The disk inlet 10a is formed in the front board of the lower chassis 10.
The disk guide 31 has a first protruding strip 31a and a second protruding strip 31b arranged on the two sides of the feed roller 14 and parallel to each other, and a third protruding strip 31c formed in a part close to the disk inlet 10a and shaped like a dogleg by inclining the central and end parts in mutually reverse directions. Each of these protruding strips 31a, 31band 31c protrudes toward the feed roller 14 to form a crest and tapered at the same slope from both ends toward the center so as to approach the feed roller 14. The presence of these tapered protruding strips enables the disk D, inserted through the disk inlet 10a, to be carried toward the inner part of the device by the feed roller 14 while being centered by the protruding strips 31c, 31b and 31a and, at the end of carriage, to be aligned to the central position of a turntable, which is intended to turn the disk D.
FIG. 2 shows a lower chassis assembly in the conventional optical disk recording/playback device. A worm gear 2 is fixed to a disk carrying motor 1, a first gear 3 meshes with the worm gear 2, a second gear 4 meshes with the first gear 3, a third gear 5 meshes with the second gear 4, and a roller gear 6 meshes with the third gear 5. The first through third gears 3 to 5 are supported by the lower chassis 10 while the roller gear 6 is fixed to the roller shaft 16 of the feed roller 14 and comes into contact with or moves away from the third gear 5 with the oscillation of the feed plate 12.
However, the conventional disk carrying unit described above involves the problem that the carriage of a disk by the feed roller 14 may not be smooth at the time of ejection depending on the type of the disk. This problem will be explained with reference to FIG. 3. At the time of inserting a disk illustrated in FIG. 3A, the worm gear 2 is turned counterclockwise, the first gear 3 clockwise, the second gear 4 counterclockwise, the third gear 5 clockwise and the roller gear 6 counterclockwise, all by the disk carrying motor 1. The feed roller 14 presses the disk on it against the disk guide 31 to carry it toward the inner part of the device. On the other hand, when ejecting the disk as illustrated in FIG. 3B, the worm gear 2 is turned clockwise, the first gear 3 counterclockwise, the second gear 4 clockwise, the third gear 5 counterclockwise and the roller gear 6 clockwise, all by the disk carrying motor 1. The feed roller 14 presses the disk on it against the disk guide 31 to carry it outward in the device. As the third gear 5 then turns counterclockwise to press the roller gear 6 downward, a downward force works on the feed roller 14 to slightly weaken the pressing force on the disk. As a result, the feed roller 14 slips relative to the roller shaft 16 depending on any warp of the disk or the coefficient of friction of the disk among other factors, leading to obstruction of smooth carriage of the disk. On the other hand when inserting the disk as illustrated in FIG. 3A, the third gear 5 turns clockwise to press the roller gear 6 upward, the pressing force on the disk is secured, resulting in smooth carriage of the disk.
The slip of the feed roller 14 relative to the roller shaft 16 is a structurally required factor, because, when the carriage of the disk by the feed roller 14 ends, the motor is still turning though the shifting of the disk is ended by a stopper, too heavy a load will be imposed on the motor unless the feed roller 14 is structured to be slidable. In addition, when the disk is ejected, the user taking out the disk after the nearer half of the disk has been ejected outside the device may force it out and damage the disk or otherwise adversely affect the operability unless the feed roller 14 is structured to be slidable.